Power line communication networks and methods employing multiple widebands

ABSTRACT

Systems and methods for communicating over a power line are configured to substantially simultaneously communicate over a plurality of wideband frequency ranges. Signals may be communicated two or from a communication node at two different frequencies simultaneously. These signals may be exchanged with different nodes and/or include independent data. In some embodiments, some of the wideband frequency ranges are above 30 MHz.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/467,141 filed on Aug. 24, 2006 and titled “Multi-WidebandCommunications over Power Lines” which claims benefit of and priority toEuropean Patent Application EP 05 256 179.2, entitled “Power lineCommunication Device and Method,” filed Oct. 3, 2005 under 35 U.S.C.119. The disclosures of the above patent applications are incorporatedby reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates to systems and methods for power linecommunication and in particular, systems and methods for wideband powerline communication.

2. Related Art

With the growing use of digital content (e.g. MP3 audio, MPEG4 video anddigital photographs) there is a widely recognised need to improvedigital communication systems. Power line communication (PLC) is atechnology that encodes data in a signal and transmits the signal onexisting electricity power lines in a band of frequencies that are notused for supplying electricity. Accordingly, PLC leverages the ubiquityof existing electricity networks to provide extensive network coverage.Furthermore, since PLC enables data to be accessed from conventionalpower-outlets, no new wiring needs to be installed in a building (ordifferent parts of a building). Accordingly, PLC offers the additionaladvantage of reduced installation costs.

Referring to FIG. 1, a household 10 typically has a distributed mainswiring system consisting of one or more ring mains, several stubs andsome distribution back to a junction box 12. For the sake of example,let the household 10 comprise four rooms 14, 16, 18 and 20. Every room14-20 may have a different number of outlets and other mainsconnections. For example, room 14 may have only one connection 22, room16 may have two connections 24, 26, room 18 may have three connections28, 30, 32 and room 20 may have six connections 34, 36, 38, 40, 42, 44.

Accordingly, there are a variety of distances and paths betweendifferent power outlets in the household 10. In particular, the outletsmost closely located to each other are those on multi-plug strips, andthe outlets furthest away from each other are those on the ends of stubsof different ring mains (e.g. power outlets in the garden shed and theattic). Communication between these furthest outlets typically passthrough junction box 12. Nonetheless, the majority of outlets associatedwith a particular application (e.g. Home Cinema) are located relativelyclose together.

Because the channel capacity of a power line and connectors attenuatesaccording to, amongst other features, the frequency of a transmittedsignal, current generation PLC systems have been developed to transmitsignals at relatively low frequencies (i.e. below 30 MHz) and therebyobtain suitable transmission distances. However, the use of such lowtransmission frequencies limits the maximum data throughput obtainableby PLC systems.

The processes of receiving analog signals and injecting modulatedsignals are treated differently by different PLC standards. Currentapproaches perform some analog conditioning to the signal-path (e.g.low-pass filtering for anti-aliasing or smoothing, or AC coupling toremove the low-frequency [<<1 KHz] high voltage content of theelectricity mains). However, there are no analog systems available forcombining two or more broadband PLC technologies that can worksimultaneously.

A number of power line communication standards have been defined. Theseinclude the Homeplug 1.0/1.1 standards, the Homeplug AV standard, theCEPCA standard and the Digital Home Standard.

In common with most communication systems, one of the main problems withprior art PLC systems is obtaining high throughput and wide coverage atreasonable implementation cost, whilst maintaining compatibility withexisting technologies. Although a few PLC systems that providetransmission rates of hundreds of megabits per second are currently onthe market, these systems have high implementation costs as they employhigh bps/Hz modulation schemes (i.e. approximately 10 bps/Hz) whichrequire high accuracy data converters, extremely linear interfaceelectronics and increase the cost of the digital implementation due tothe computational complexity of the modulation.

There is, therefore, a need for improved PLC systems that overcome theabove and other problems.

SUMMARY

Various embodiments include systems and methods of communicating over apower line by simultaneously sending and/or receiving data over aplurality of wideband frequency ranges. Various embodiments include apower line communication network comprising at least one power linecommunication device configured to use a plurality of wideband frequencyranges.

Some embodiments include a system for communicating over a power linecomprising a device for communicating over a power line, systems forconnecting to the power line, and systems for transmitting data from thedevice to appropriate applications or transmitting data from theapplications to the device.

In some embodiments, the power line communication device is configuredto improve the throughput/coverage/cost performance trade-off of a powerline network, when compared with current-generation PLC networks, byspreading the transmission of data into a plurality of independentwideband frequency bands that can be operated simultaneously andindependently.

Furthermore, the power line communication device also optionallyfacilitates inter-operability by using one or more of the frequencybands to facilitate communication with nodes employing previous powerline technologies. In this way, the power line communication deviceprovides a way of creating a scalable implementation of a network wherenodes of previous technologies work, without loss of performance,together with new-generation power line technologies.

More particularly, the power line communication device can enable theuse of frequencies above 30 MHz whilst maintaining compatibility withcurrent worldwide EMC regulations and standards. This is achieved byusing a signal of frequency less than 30 MHz (as currently used by thepower line standard and/or regulations) and at least one other signal offrequency greater than 30 MHz without compromising the performance ofany of the signals due to interference.

The result is a new PLC system that facilitates interoperability with apre-existing power line communication technology within a wideband(currently in the frequency range of 1 MHz to 30 MHz) and provides theability to extend the system into new significantly higher frequencywidebands (e.g., frequencies between 30 MHz and 1 GHz) to improve theoverall throughput of the resulting communication system whilesimplifying the implementation of any single given wideband.

The power line communication device comprises a network interface devicethat employs an analog signal separating device (e.g., analog filter) toseparate the paths of different wideband signals received from the powerline before converting them to their digital representation. The analogsignal separating device also separates the paths of different widebandsignals to be transmitted on the power line (after their conversion fromtheir digital representation). The network interface device optionallyemploys TDMA (time division multiple access) and/or FDMA (frequencydivision multiple access) as a scheme for enabling co-existence,synchronisation and/or bi-directional transmission.

The analog signal separating device is configured from block elementscomprising discrete and/or integrated electronic components and thenatural characteristics of the wiring and/or printed circuit boardtraces used to interconnect said components.

In some embodiments, the power line communication device is employed ina system that is configured to be expandable to provide greater overallbandwidth, but with widely differing injected power levels in thedifferent frequency ranges, and/or to coexist and be inter-operate withother pre-existing technologies on the same network.

In various embodiments, each of the pre-existing and new-generationpower line technologies is configured to implement different modulationschemes (e.g. OFDM, CDMA (code division multiple access) and/or OWDM(orthogonal wavelet domain modulation)), either alone or incombination). Depending on its channel state, the power linecommunication device can send data through any or all of the widebands.Furthermore, depending on its network function, the power linecommunication device can distribute the data from a single source ormesh it together with data repeated from another node on the network.

In various embodiments, each node on the power line communicationnetwork is an apparatus that integrates the analog signal separatingdevice and modem converters (e.g. DFE (Digital Front End), MAC (MediaAccess Control), etc.) as part of the power line network interfacedevice; and an application such as a computer, mass storage device,display device, speaker, DVD (Digital Versatile Disc) player, PVR(Personal Video Recorder), etc.; and/or an interface to connect anapplication such as a digital audio interface, digital video interface,analog audio interface, analog video interface, Ethernet interface,IEEE1394/Firewire/iLink interface, a USB (Universal Serial Bus)interface, and/or the like.

In some embodiments, the power line communication device is configuredto use a signal (in line with the current standards and injected powerregulations) of frequency less than about 30 MHz and at least one othersignal of frequency greater than 30 MHz without compromising theperformance of any of the signals due to interference. This feature canenable the power line communication device to increase throughput whilstenabling interoperability with previous PLC technologies.

An advantage of using a low frequency band is the possibility for highercoverage (e.g., communication over greater distances) than thatachievable with a high frequency band, due to the greater injected powerallowed by the regulations and the lower channel attenuation. Anadvantage of using a high band is the higher throughput achievable dueto the greater available bandwidth.

In some embodiments, the power line communication device is configuredto exploit the natural topology of power line networks in a home,wherein a group of related devices and sockets are typically clusteredclose to each other (e.g. plasma screen, DVD player and speakers in aliving room) and other clusters of devices and sockets are clusteredelsewhere (e.g. desktop printer, scanner and ADSL router in a homeoffice). Such household topologies can benefit from the high throughputshort-range coverage provided by the high band (which is simultaneouslyand independently available within each of the clusters) whilst the lowband can be used to carry the majority of data communications betweenthe clusters. It will also be appreciated that some communication nodesmay benefit from communications on both bands.

In some embodiments, the parallel use of multiple widebands enables theuse of different injected power levels, receiver sensitivities,transmission times, symbol lengths and modulation techniques to optimisethe performance and cost of each wideband, leading to a better costperformance solution even though it is necessary to provide more thanone analog and digital front-end. Part of the implementation costadvantage arises from the ability to reduce the bps/Hz in each wideband,but still maintain throughput performance because of the additionalbandwidth available. This effect non-linearly compensates for the costof implementing more than one wideband communication technology.Furthermore, the reduced coverage of the high band(s) is offset by theparallel use of the low band (with its greater allowable injectedpower). For instance, in various embodiments, the power linecommunication device may be used to provide Gbit/s performance at alower cost than current 200 Mbps systems, by using lower bps/Hzmodulation schemes (i.e. approximately 5 bps/Hz rather than 10 bps/Hz)over multiple widebands.

In various embodiments, a network interface device is configured toemploy analog signal separation and include multiple analog front-ends.The use of analog signal separation, based on frequency, enables eachwideband technology to optionally operate independently, and may includeone or more of the following features:

(a) The network interface device is configured for independentperformance optimization of the analog to digital converters (ADCs),digital to analog converters (DACs) and PGA or line drivers employed inprocessing the signals from a given frequency band, wherein theoptimisation is performed for the required bandwidth, linearity anddynamic features of the frequency band and optimised for the powerlevels required to match EMC regulations and/or coverage of thefrequency band;

(b) The network interface device is configured for the power linecommunication device to maintain compatibility and inter-operabilitywith existing standards using one of the frequency bands, whilstexploiting independently (and without causing prohibitive interferenceto) another frequency band for additional communication (for example,the Homeplug AV standard which uses frequencies in the range of 2 MHz-28MHz could work simultaneously with another standard that usesfrequencies greater than 30 MHz);

(c) The network interface device is configured to increases the capacityof the power line communication device by allowing the inclusion ofadditional widebands that do not need to use the same modulationtechnology, but can use modulation technologies that best match the newfrequency bands' power line channel characteristics; and

(d) The network interface device is configured to allow differentwidebands to operate without synchronisation to or dependence on otherwidebands.

In various embodiments, the power line communication device is alsoconfigured to allow other network technologies to be layeredindependently on top of it, for example:

(a) combinations of data from different bands at various differentcommunication levels whether in the digital front-end, the MAC layer orthe application layer;

(b) using notches in the modulation scheme to limit emissions of certainfrequencies within one of the analog defined wideband frequencies;

(c) using repeaters in a node to re-transmit on the same or a differentfrequency band;

(d) using a range of modulation schemes such as OFDM, CDMA and/or ODWM;and/or

(e) forming point-to-point, point-to-multipoint and ormultipoint-to-multipoint communication patterns.

In some embodiments, the network interface device can combine andpartition data communicated across different paths to maximiseperformance, coexistence and interoperability whilst minimizing systemcost.

Various embodiments of the invention include a method comprisingreceiving digital data form one or more applications, encoding a firstpart of the digital data into a first signal within a first widebandfrequency range, at least part of the first wideband frequency rangebeing less than 30 MHz, encoding a second part of the digital data intoa second signal within a second wideband frequency range, at least partof the second wideband frequency range being greater than 30 MHz,combining the first signal and the second signal to generate a combinedsignal, and sending the combined signal over a power line.

Various embodiments of the invention include a method comprisingreceiving a signal over a power line, separating the received signalinto a first signal component in a first wideband frequency range and asecond signal component in a second wideband frequency range, each ofthe first wideband frequency range and the second wideband frequencyrange being at least 10 MHz wide, separately processing the first signalcomponent and the second signal component to extract digital data, andproviding the digital data to one or more applications.

Various embodiments of the invention include a communication networkcomprising a first communication node configured to communicate using afirst wideband frequency range at least 10 MHz wide and a secondwideband frequency range at least 5 MHz wide, a second communicationnode configured to communicate with the first communication node over apower line by simultaneously using both the first wideband frequencyrange and the second wideband frequency range.

Various embodiments of the invention include a communication devicecomprising a coupling configured to communicate data over a power line,a first part of the data being communicated using a first widebandfrequency range and a second part of the data being communicated using asecond wideband frequency range separate from the first widebandfrequency range, the first part of the data being independent from thesecond part of the data, first logic configured to process the firstpart of the data, and second logic configured to process the second partof the data.

Various embodiments of the invention include a communication networkcomprising a first communication node configured to communicate using afirst wideband frequency range, a second communication node configuredto communicate using a second wideband frequency range separate from thefirst wideband frequency range, and a third communication nodeconfigured to simultaneously and independently receive communicationfrom the first communication node over a power line using the firstwideband frequency range and from the second communication node over thepower line using the second wideband frequency range.

Various embodiments of the invention include a method comprisingcommunicating first data between a first communication node and a secondcommunication node over a power line, using a first wideband frequencyrange, and communicating second data between the first communicationnode and a third communication node over the power line, using a secondwideband frequency range separate from the first wideband frequencyrange, the first data and the second data being communicatedsimultaneously.

Various embodiments of the invention include a method comprising sendinga first communication from a first communication node over a power lineusing a first wideband frequency range, the first communicationincluding data configured to identify a second communication nodeconfigured to communicate in the first wideband frequency range,receiving a response to the first communication from the secondcommunication node, sending a second communication from the firstcommunication node over the power line using a second wideband frequencyrange, the second communication including data configured to identify athird communication node configured to communicate in the secondwideband frequency range, receiving a response to the secondcommunication from the third communication node, and determining acommunication strategy based on the response to the first communicationand the response to the second communication.

BRIEF DESCRIPTION OF THE DRAWINGS

Multiple embodiments of the invention will now be described by way ofexample only with reference to the accompanying Figures in which:

FIG. 1 is a block diagram of a prior art residence;

FIG. 2A is a block diagram of an exemplary network comprising aplurality of nodes, some of which have multiple wide-band capabilities,according to various embodiments;

FIG. 2B is a block diagram of the exemplary network of FIG. 2A,depicting two simultaneous, bi-directional communication links therein,according to various embodiments;

FIG. 2C is a block diagram of the exemplary network of FIG. 2A,depicting three simultaneous communication links therein, according tovarious embodiments;

FIG. 2D is a block diagram of a first stage of a one packet datatransmission procedure implemented on the network of FIG. 2A, accordingto various embodiments;

FIG. 2E is a block diagram of a second stage of the one packet datatransmission procedure shown in FIG. 2D, according to variousembodiments;

FIG. 3 is a block diagram of the hardware architecture of a modem in apower line communication device, according to various embodiments;

FIG. 4A is a block diagram of signal paths in a single coupling unitprior art power line transmission system, according to variousembodiments;

FIG. 4B is a block diagram of signal paths in a dual coupling unit priorart power line transmission system, according to various embodiments;

FIG. 4C is a block diagram of signal paths in a first embodiment of thepower line communication device:

FIG. 4D is a block diagram of signal paths in a second embodiment of thepower line communication device;

FIG. 4E is a block diagram of signal paths in a third embodiment of thepower line communication device;

FIG. 4F is a block diagram of signal paths in a fourth embodiment of thepower line communication device;

FIG. 5A is a block diagram of a first integrated circuit embodiment ofthe power line communication device;

FIG. 5B is a block diagram of an alternatively partitioned secondintegrated circuit embodiment of the power line communication device;

FIG. 5C is a block diagram of a further alternatively partitioned thirdintegrated circuit embodiment of the power line communication device;

FIG. 6A is a circuit diagram of an exemplary capacitive coupling unitused in the power line communication device, according to variousembodiments;

FIG. 6B is a circuit diagram of an exemplary inductive coupling unitused in the power line communication device, according to variousembodiments;

FIG. 7A is an exemplary power transmission spectrum of three power linetechnologies, according to various embodiments;

FIG. 7B depicts the frequency characteristics of an exemplary set ofanalog filters for use in separating the widebands used by the threepower line technologies depicted in FIG. 7A, according to variousembodiments:

FIG. 7C shows the signal isolation provided by a second analog filterFilt_(B) (shown in FIG. 7B) to the Tech_(B) signal (shown in FIG. 7A)according to various embodiments;

FIG. 8A is a block diagram of a household with a simple initialinstallation of the power line communication network of the third aspectof the invention, according to various embodiments;

FIG. 8B is a block diagram of a household with a more complexinstallation of the power line communication network, according tovarious embodiments;

FIG. 9 illustrates a method by which one communication node can discoverother communication nodes on a network using different widebandfrequency ranges, according to various embodiments;

FIG. 10 illustrates a method in which a first communication nodecommunicates simultaneously with both a second communication node and athird communication node, according to various embodiments;

FIG. 11 illustrates a method in which a communication node receivessimultaneous signals using at least two different widebands, accordingto various embodiments; and

FIG. 12 illustrates a method in which a communication node sendssimultaneous signals using at least two different widebands, accordingto various embodiments.

DETAILED DESCRIPTION

For the sake of clarity, the term “power line” will be used herein torefer to low voltage household mains distribution cabling (typically100-240 V AC power) or any other distributed electrically conductivecabling (i.e. AC or DC), that is capable of passing power to appliancesconnected to it. Furthermore, the term “power line technology” will beused herein to refer to a specification that when implemented as aseries of network interface devices connected to a power line, enablesthe devices to bi-directionally communicate with each other usingsignals superimposed on the power distribution signal already present onthe power line.

The term “network interface device” will be used herein to describe anapparatus that implements either fully or partially, a communicationstechnology, such as a power line technology, to enable the apparatus tocommunicate with other devices connected to the same network (such as apower line), regardless of whether or not the apparatus is integratedwith other apparatuses or functions within a single enclosure. For thesake of clarity, a device connected to a power line network will begenerically known herein as a “node”.

The term “coverage” will herein be used to refer to the maximum distancebetween two nodes at which data transmitted therebetween is stilldetectable by either node. In addition, the term “throughput” will beunderstood to represent the rate at which nodes send or receive data ona network.

For the sake of clarity, in terms of explanation of operation of thepower line communication device around current power line technologies,a wideband frequency band used in the power line communication devicewhose frequency of less than about 30 MHz, will be known herein as a“low band”. Similarly, a wideband frequency band(s) used in the powerline communication device whose frequency is greater than about 30 MHzwill be known herein as “high band(s)”.

For completeness and since the present invention relates to widebandcommunication, the term “wideband” will be used herein to refer to afrequency band or range used by a power line technology signal,characterised by having a bandwidth of greater than, or equal to, 5 MHzfrom the first (lowest) frequency to the last (highest) frequency of theband irrespective of the presence of notches. However, in variousembodiments, wideband may have bandwidths of at least 7, 10, 12, 15, 20,100 or 250 MHz. Similarly, the term “narrowband” will be used to referto a frequency band used by a power line technology signal,characterised by having a bandwidth of less than 5 MHz. A wideband mayinclude many different carrier channels used to convey data. Forexample, in various embodiments, widebands include more than 25, 50, 100or 200 data channels.

The term “transmission time” is herein used to describe the maximumamount of time it takes to transmit a single co-existent message. Thetransmission time includes, but is not limited to, a start oftransmission marker time (if any), a synchronisation time (if any), achannel access resolution time (if any), a negotiation time (if any), amessage transmission time, an acknowledge transmission time (if any) andan end of transmission marker time (if any).

The term “notch” will be used herein to refer to a frequency band wherethe energy level of a power line technology signal has been deliberatelyreduced to prevent interference with other users of the spectrum(whether on or off the power line). Notches are characterized by havinga narrower bandwidth than the power line technology signal itself andare generally implemented by digital or analog signal separating devicewithin a single digital signal processing block or analog front end.

For the sake of clarity, the term “sub-band” will be used herein torefer to a frequency band where a power line technology signalcharacteristic differs from the characteristics of the power linetechnology signal in the remainder of the signal's bandwidth. Suchdifferences can include the optional or mandatory presence of thesub-band, the signal power level of the sub-band and the directionalityof the sub-band. Sub-bands are characterized by having a narrowerbandwidth than the power line technology signal itself. The use ofoverlapping sub-bands in OFDM enables notches to be created, wherein asub-band is disabled if the reception of the sub-band is heavilyimpaired or the sub-band can interfere with another service.Furthermore, OWDM can simplify the notching out of carriers due to itslower side lobes.

For the sake of simplicity, the term “transmitter signal path” will beused to refer to the path of a signal transmitted from an apparatus tothe power line. Similarly, the term “receiver signal path” will be usedto refer to the path of a signal received by an apparatus from a powerline. On a related note, it may not be necessary to perform theisolation on both the receiver and transmitter signal paths (dependingon the specifications of the analog components and the modulationtechniques employed therein).

For the sake of clarity, the power line communication device of thepresent invention will be referred to herein at times as an “improvedpower line communication device”. Similarly, the network interfacedevice of the improved power line communication device will be referredto herein as an “improved network interface device”. Finally, the powerline communication network comprising nodes that are improvedcommunication devices will be known herein at times as an “improvedpower line communication network”.

The term “separate,” as used herein with respect to widebands, is tocharacterize widebands that do not use, except incidentally, the samefrequencies for communication data or commands. Widebands may beseparate but interleaved, e.g., overlapping.

The term “simultaneously” is used herein with respect to communicatingdata to indicate that at least part of first data or commands arecommunicated using a first wideband at the same time as at least part ofsecond data or commands are communicated using a second wideband.Simultaneous transmission is contrasted with systems that alternate orinterleave the use of frequencies, one after the other or hopping fromone to the other.

The term “independent” is used herein with respect to data transmittedto indicate that data transmitted using one wideband does not depend ondata simultaneously transmitted using another wide band. Independentdata transmission can include, for example, data sent to or receivedfrom different locations. Data in which alternative bits are transmittedusing different frequencies is not independent because the bits aredependent on each other to form a useful byte.

It will be appreciated that the specific network and other examplesdescribed in these sections are used for illustrative purposes only. Inparticular, the examples described in these sections should in no way beconstrued as limiting the improved power line communication device.

Some embodiments of the improved power line communication networkcomprise a plurality of nodes of which some employ a network interfacedevice that enables simultaneous and independent communication over twoor more widebands, to similar multi-wideband nodes or conventionalnodes. A first wideband optionally comprises frequencies of less than 30MHz, in line with the current standards and injected power levels (andwill herein be known as a low band) and the other wideband(s) comprisefrequencies of greater than 30 MHz (and will herein be known as highband(s)). Alternatively, both a first and second wideband may comprisefrequencies greater than 30 MHz. This enables power line technologies tobe optimised for each of the widebands, so that the trade-off betweencost, coverage and throughput will be superior to that achieved by apurely mono-wideband approach.

In particular, the modulation schemes for each technology used withinthe improved power line communication network can be optimised for cost.For instance it may not be necessary to use a particularly highmodulation density (bps/Hz) in the low band to enhance throughputbecause the low band can work in parallel with the inherently highthroughput high band(s).

The improved power line communication network provides inter-operabilitywith prior art power line technologies by also supporting communicationbetween multi-wideband nodes and mono-wideband nodes (that use one ofthe power line technologies supported in the low band or high band(s)and communicate at frequencies in the low or high band(s).

The improved network interface device may be part of an external modemapparatus or embedded within another apparatus (e.g. computer, TV etc.).However, regardless of the manner in which an improved network interfacedevice is included within a node, the device remains physicallyconnected to electrically conductive cabling (that passes AC or DCpower) and is capable of transmitting digital data across the cablingusing either or all of the low and high bands.

In accordance with current regulatory standards, low band signals may betransmitted with a power spectral density of approximately up to −50dBm/Hz whereas high band signals may only be transmitted with a powerspectral density that causes emissions in this frequency band to belower than −80 dBm/Hz. Accordingly, signals in the low band may betransmitted with a power spectral density approximately one thousandtimes greater than signals in the high band. Consequently, if signals inboth of these bands were to be transmitted simultaneously, without usingsome form of analog frequency isolation, the dynamic range and voltagecompliancy requirements of the high band signals would be significantlyincreased.

However, the potential for interference or saturation of a lower powersignal may be even more problematic. In particular, if one of the bandsis used to receive a line-attenuated signal whose power level is closeto the noise on the power line (i.e. −150 dBm), while at the same time,the other band is used to transmit a signal at its maximum allowabletransmission power, the isolation required to prevent the signals fromthe two bands from interfering with each other would be approximately100 dB. However, this is beyond the current state of the art analogimplementations and would have high implementation costs.

In summary the isolation required to effectively allow simultaneous andindependent communication of high and low bands falls into three maincategories:

(1) isolation to prevent the strength of a signal received over thenetwork in one wideband from saturating the receiver of the otherwideband;

(2) isolation to prevent the transmitter of one band from interferingwith the reception of another band; and

(3) isolation to prevent the degradation of the transmitter for one bandwhen another band is being transmitted.

In view of the above, the improved network interface device employs ananalog signal separation device to isolate the paths from the power lineconnection to an apparatus; to data-converters for each wideband. One ofthe most efficient ways of providing this isolation is by high-passfiltering or band-pass filtering high band signals, whilst minimisingout-of band signals in the low band (using high linearity components andpossibly analog low-pass smoothing or anti-aliasing).

Signals in the high band and the low band can use the same or differentmodulation techniques (e.g. OFDM, CDMA and/or ODWM) or time divisionschemes to facilitate co-existence and/or bi-directional communication.In one possible scenario, the low band could employ a modulation schemethat is inter-operable with one of the existing power line modemstandards or proposals, whilst the high band is used for performanceexpansion beyond previous standards. Data and/or control can be passedthrough one or both of the widebands simultaneously and via a pluralityof nodes in the form of a repeater (e.g., relay) network.

There are many different ways of implementing the improved power linecommunication device. For example, the improved power line communicationdevice may be implemented on one or more integrated circuits (whetherdedicated to the modem function or as part of an application system on achip), and in combination with the characteristics of passive componentsand interconnects. However, the implementation of the analog signalseparating device to separate the low band and high band(s)) employs acombination of the components in the different signal paths, whetherpassive or active, integrated or discrete. In particular, it is possiblefor the widebands:

(a) to share part of their paths (e.g. through a coupling unit); or

(b) to be joined only at the power line; and/or

(c) to be at opposite ends of the apparatus.

It is also possible to expand the improved power line communicationdevice to communicate on more than two widebands. Similarly, it is alsopossible for the widebands to overlap slightly if required, and to bedifferent in frequency ranges or bandwidths to those cited in thespecific description.

Referring to FIG. 2A, a network 50 that represents the improved powerline communication network, comprises a plurality of nodes 54-76. Someof the nodes comprise the improved power line communication device andaccordingly implement more than one PLC technology. Nodes that do notinclude the improved network interface device can only implement one PLCtechnology. For the sake of simplicity, nodes that can only implementone PLC technology will be known herein as “mono-wideband nodes”.Similarly, nodes that can implement more than one technology will beknown herein as “multi-wideband nodes”.

Three different PLC technologies are employed for communication on thenetwork, namely Tech_(A), Tech_(B) and Tech_(C). Nodes 54 and 76comprise the improved network interface device and are capable ofimplementing PLC technologies Tech_(A) and Tech_(B). Nodes 58 and 66comprise the improved network interface device and are capable ofimplementing PLC technologies Tech_(B) and Tech_(C). Finally, nodes 60and 68 comprise the improved network interface device and are optionallycapable of implementing all three PLC technologies.

The remaining nodes (namely nodes 56, 62, 64, 72 and 74) do not comprisethe improved network interface device and thus can only implement one ofthe PLC technologies. In particular, nodes 62 and 70 implement PLCtechnology Tech_(A) only, nodes 56 and 72 implement PLC technologyTech_(B) only, and nodes 64 and 74 implement PLC technology Tech_(C)only. Optionally, all of the communication between the nodes on thenetwork 50 takes place through a common power line 52.

In some embodiments, the improved power line communication networksupports communication between nodes that implement different PLCtechnologies. In contrast, prior art PLC systems can only supportcommunication between nodes that implement identical PLC technologies(e.g. nodes 56 and 72), even if the nodes in question co-exist on anetwork with nodes that implement other PLC technologies (e.g. nodes 64and 74).

FIG. 2B shows two simultaneous, bi-directional and non-interferingcommunication links in the network 50 of FIG. 2A. A first communicationlink 80 is a point-to-point communication link between nodes 54 and 68which simultaneously uses the high band and low band to enablesimultaneous communication of both Tech_(A) and Tech_(B) messagesbetween the two nodes.

It should be noted that whilst node 68 is optionally capable ofimplementing all three technologies (i.e. Tech_(A), Tech_(B) andTech_(C)) only the Tech_(A) and Tech_(B) capabilities of node 68 areused in the first communication link 80. Furthermore, it should be notedthat the first communication link 80 can re-distribute data from theTech_(A) and Tech_(B) technologies across the high band and the low bandin accordance with the current network characteristics (e.g. channelimpairments).

A second communication link 82 connects nodes 68, 58, 60, 74 and 64.Since nodes 64 and 74 are only capable of implementing PLC technologyTech_(C), the second communication link 82 only supports communicationsof the Tech_(C) technology.

The presence of the two communication links 80 and 82 allows nodes 68,58, 60, 74 and 64 to establish communication (through the secondcommunication link 82) at the same time that node 68 is communicatingwith 56 (through the first communication link 80). In other words, thenetwork arrangement depicted in FIG. 2B, enables two simultaneous andconcurrent communications to be performed, wherein the firstcommunication link 80 enables dynamic data transmission and receptionusing technologies Tech_(A) and/or Tech_(B) and the second communicationlink 82 enables dynamic data transmission and reception using technologyTech_(C).

FIG. 2C shows three concurrent and simultaneous communication links 84,86 and 88 in the network 50 of FIG. 2A. The first communication link 84provides a bi-directional point-to-multipoint connection between node 54and nodes 68 and 70. Since node 70 is only capable of implementingtechnology Tech_(A), the first communication link only supportscommunications of the Tech_(A) technology. Meanwhile a secondcommunication link 86 enables communication between nodes 56 and 72 oftechnology Tech_(B) with technology Tech_(A) using a co-existencestrategy such as Time Division Multiple Access (TDMA) (i.e. a multipleaccess technique where only one transmitter transmits on a particularchannel at any given time).

Finally, a third communication link 88 supports communication ofTech_(C), wherein these communications are conducted in a differentwideband that does not interfere with the other communication links.

Referring to FIG. 2D, let there be a first communication link 90 betweennodes 68, 58 and 60 of the network 50 depicted in FIG. 2A. The firstcommunication link 50 is bi-directional and supports communication ofTech_(B) and Tech_(C). Furthermore, let there be a simultaneous secondcommunication link 92 between nodes 70 and 62 of the same network 50.The second communication link 92 supports communication of Tech_(A).

For the sake of example, let there be a message originating in node 58that to be distributed to the nodes of the network 50. Nodes such as 68,60 and 66 that support Tech_(B) and Tech_(C), can demodulate and receivea message from node 58. However, the remaining nodes on the network 50cannot receive the message. To solve this problem, a two-stagecommunication process is implemented in which:

(i) in the first stage, the message is transmitted from node 58 to 68,using PLC technologies Tech_(B) and Tech_(C); and

(ii) in the second stage, the message is re-transmitted (e.g., relayed)by node 68, using its technology capabilities, so that optionally all ofthe nodes on the network 50 can receive and demodulate the message.

Repeaters can also be used to increase the coverage of a giventechnology (when a node can detect its neighbouring node, but notfurther nodes thereafter).

FIG. 2E is a block diagram of a second stage of the one packet datatransmission procedure shown in FIG. 2D. This second stage optionallyincludes a broadcast made simultaneously in more than one wideband. Assuch, the broadcast may include more that one communication standard.

Referring to FIG. 3, a modem 80 in an improved network interface devicecomprises N blocks 82A-82N corresponding to each of the PLC technologiessupported by the node. In other words, block 82A corresponds with theTech_(A) technology, block 82B corresponds with the Tech_(B) technology,and so on, until block 82N, which corresponds with the Tech_(N)technology.

Each block 82A-82N comprises the first (PHY) and second (MAC) layers ofthe OSI (Open Systems Interconnection) stack for each technology. Forexample, the block 82A comprises the blocks PHY_(A) and MAC_(A).Similarly, the block 82B comprises the blocks PHY_(B) and MAC_(B). Themodem 80 further comprises a data distribution block 84, whichdistributes data amongst the blocks 80A and 80N in accordance with thetechnology of the signal and current network traffic characteristics.

When used for transmission, signals from each technology supported by anode are processed by an analog filter bank (not shown). The operationof the analog filter bank will be described in more detail later. Theprocessed signals 86 are forwarded to the data distribution block 84 fordistribution amongst the blocks 82A-82N. The outputs from the blocks82A-82N are combined in a coupling/decoupling stage 88 from which theyare injected into a power line 90.

When used for receiving a signal from the power line 90, the couplingdecoupling stage 88 decouples the component signals for each supportedPLC technology. The decoupled signals are processed through blocks82A-82N and forwarded through the data distribution block 84 to theappropriate applications running on the node.

Each of the PHY blocks (PHY_(A)-PHY_(N)) may have a feedback signal92A-92N which provides information regarding the usage of each of thetechnology signal paths. This information is used by the datadistribution block 84 to redistribute the data flow amongst the Navailable blocks 82A-82N. It should also be noted that parts of the MACand PHY blocks (PHY_(A)-PHY_(N)) and (MAC_(A)-MAC_(N)) may be capable ofsharing resources.

Referring to FIG. 4A, in a first form of a prior art power linetransmission system, a power line 100 is connected to a single couplingunit 102, which has high-pass transmission characteristics to enable therejection of the AC line frequency of the power line 100. The couplingunit 102 is, in turn, connected to receiver and transmitter paths 104,106, which are isolated during half duplex phases using an RX/TX switch108.

The receiver path 104 typically comprises a band-limiting anti-aliasingfilter 110, a programmable gain amplifier (PGA) 112, and an ADC 114. Theresulting digital signal 116 is then demodulated 118. The anti-aliasingfilter 110 may be in a different order and may be partially orcompletely provided by the bandwidth of the PGA.

The transmitter path 106 typically comprises a line driver 120 (whichmay or may not be capable of operating in high impedance mode) and aband-limiting smoothing filter 122. The band-limiting smoothing filter122 limits the power of harmonics (in the out-of-band range) in theanalog signal (the harmonics being produced by the operation of a DAC124 on a received digital signal 126 that had previously been modulated128). It will be realised that part of the modulation and demodulationschemes 118, 128 could also be performed in the analog domain.

Referring to FIG. 4B a slightly different form of a prior art singlewideband system employs separate transmitter and receiver coupling units130, 132. A TX/RX switch is not required in this form of the prior artpower line transmission system, as either the impedance of the linedriver 120 does not significantly represent an extra impedance load tothe power line 100 or the line driver 120 itself is capable of goinginto a high impedance mode.

Referring to FIG. 4C, the improved network interface device comprisestwo or more analog front-ends separated into two low band analog pathsLB₁ and LB₂ and two high band paths HB₁ and HB₂, by coupling units 142,148, 154 and 160 respectively.

The analog filtering characteristics of the different paths (includingthe coupling units 140-146 and the active components) are designed topass the signal of a given band whilst rejecting the signals of theother bands. The modulation schemes of each technology 152, 154 may bethe same or different, as may be the demodulation schemes 148, 150.

Referring to FIG. 4D in a second embodiment of the improved networkinterface device there are two coupling units 166, 176, wherein couplingunit 166 is used for low band communication and coupling unit 176 isused for high band communication. In addition to the optimisation of thelow band paths (167-171 and 172-175) and the high band paths (177-181and 182-185) for the power, frequency and modulation schemes ofdifferent PLC technologies, the coupling units 166, 176 can be optimisedto have different pass-frequency characteristics.

Referring to FIG. 4E, in a third embodiment of the improved networkinterface device, there are two coupling units 186 and 190, whereincoupling unit 186 is used for reception and coupling unit 190 is usedfor transmission. However, each high band path (188-191 and 203-206) isisolated from the low band paths (192-195 and 197-201) by deliberatelyinserted filters 187, 202 with high pass or band pass characteristics.

FIG. 4F shows a fourth embodiment of the improved network interfacedevice, applied to two different wideband technologies as in FIG. 4E.Whilst there are many possible other combinations, it is not necessaryfor there to be separate paths and converters for the high band pathsand low band paths in either the receiver or transmitter, ascommunications in one direction may benefit more from the improvednetwork interface device than communications in the other direction.

The improved network interface device comprises one coupling unit fortransmission 218 and one for reception 208. The high band is isolatedfrom the low-band on the receiver path, by deliberately inserted filters209 with high-pass or band-pass characteristics. However, thetransmitter modulation schemes are combined in the digital domain 222A,222B and then passed through a very high performance DAC (digital toanalog converter) 221, smoothing filter 220 and line driver 219.

Referring to FIG. 5A, an exemplary integrated circuit 250 implementationof the improved network interface device comprises two analog front endsAFE_(A), AFE_(B) for the two widebands of the improved power linecommunication device. The exemplary integrated circuit 250 alsocomprises a logic element 226 configured to implement the differentpower line modem technologies (including DFE and MAC) and provide adigital interface to the next stage application 228 in the device.

The high band analog front end (AFE_(B)) contains high band converters230, 232 and active interface electronics (i.e. a PGA 234 and linedriver 236) and connects to the power line via a coupling unit alongpath 238. The low band analog front end (AFE_(A)) comprises low bandconverters 240, 242 and active interface electronics (i.e. a PGA 244 andline driver 246) and connects to the power line via a coupling unitalong path 248.

A digital representation of the signal to be sent on the low band andhigh band is produced in the logic element 226 and is present atinterfaces 250, 252 to the analog front ends AFE_(A), AFE_(B).

Referring to FIG. 5B, in an alternative integration partition 300 of theintegrated circuit implementation of the improved network interfacedevice, there are two integrated circuits, namely a digital modemintegrated circuit 302 and an analog modem integrated circuit 304containing the two analog front ends AFE_(A), AFE_(B). The analog modemintegrated circuit 304 may be configured in several parts, asillustrated in FIG. 5B, or alternatively as a single component.

Referring to FIG. 5C, in another integration partition 400 of theintegrated circuit implementation of the improved network interfacedevice, the analog front end of each wideband is split into dataconverters Conv_(A), Conv_(B) and interface circuits I/Face_(A),I/Face_(B). In this case, the converters Conv_(A), Conv_(B) areintegrated with the digital logic 401 of the power line modem in oneintegrated circuit 402 while the higher frequency current/voltageinterface circuitry is provided in another integrated circuit 404.

It will be appreciated that there are numerous other possibilitiesincluding the embedding of all or part of the active electronics withinother devices in the system, or the use of discrete blocks for variousblocks.

As discussed elsewhere herein, a coupling unit can have frequencycharacteristics. Referring to FIG. 6A, a capacitive coupling unit 500comprises X1 type capacitors 502 that are used to couple a signal source504 (via an isolating transformer 506) onto a power line 508. In thiscase, the impedances of the transformer 506, capacitors 502, signalsource 504 and the power line 508 determine the frequency response ofthe capacitive coupling unit 500.

Referring to FIG. 6B, an inductive coupling unit 520 comprises a signaltransformer 522 that inductively couples a signal 524 in tandem with aY1 type capacitor 526. The inductive coupling unit 520 is roughlyequivalent to the capacitive coupling unit 500 (depicted in FIG. 6A),with the respective impedances of the transformer 522, capacitor 526,signal source 524 and power line 528 determining the frequency responseof the inductive coupling unit 520.

Furthermore, a low-pass filtered version of the power line 508, 528 canbe used within the improved network interface device to provide a powersupply. It is also possible to implement higher order filters in thecoupling units with more passive components. Nonetheless, it will beappreciated that it is possible to employ many other types of couplingunit (e.g. optical coupling units) in the power line network interfacedevice.

FIGS. 7A to 7C illustrates the exemplary frequency spectra of a numberof different power line technologies, and demonstrates how an analogsignal separating device could be used to separate the signals of agiven technology (from the signals of the other technologies) into aparticular signal path.

Referring to FIG. 7A, a first technology Tech_(A) has a transmissionpower P_(A) and a wide-band 540 delimited by frequencies f_(A1) andf_(A2). The wide-band 540 has internal notches 542 to comply with EMCregulations. A second technology Tech_(B) has a transmission power ofP_(B) and a wide-band 544 delimited by frequencies f_(B1) and f_(B2).The wide-band 544 also has a notch 546 to comply with EMC(Electromagnetic Compatibility) regulations. It should be noted thatf_(B1) may be greater than f_(A2) to avoid band-overlapping. Finally, athird technology Tech_(N), has transmission power P_(N) and a wide-band548 delimited by frequencies f_(N1) and f_(N2). The wide-band 548 alsohas a notch 550 to comply with regulations.Referring to FIG. 7B a first, second and third analog filter (namelyFilt_(A), Filt_(B) and Filt_(N) respectively) respectively isolate thesignals from each of Tech_(A), Tech_(B) and Tech_(N), from the signalsfrom the other technologies. The analog filter characteristics areapplicable to the transmitter and/or the receiver of each technologywithin a node.

The first analog filter Filt_(A) is defined by passband start and endfrequencies f_(A3), f_(A4). Similarly the second analog filter Filt_(B)is defined by passband start and end frequencies f_(B3) and f_(B4).Finally, the third analog filter Filt_(N) is defined by passband startand end frequencies f_(N3) and f_(N4).

In one embodiment, the start of at least one of the passbands of theanalog signal separating device of the power line communication deviceis between 1 MHz and 30 MHz, and is at least 10 MHz in width.Optionally, at least one of the other widebands includes signals at afrequency greater than 30, 40, 50, 75, 100, 200 or 500 MHz, andoptionally less than 1 GHz. The difference between the passband andstopband for any one of the elements of the analog signal separatingdevice may be more than 6 dB.

It should be noted that it is possible for different analog filters tooverlap (e.g. f_(A4)>f_(B3)), or not to overlap (e.g. f_(B4)<f_(N3)). Itshould also be noted that it is not necessary for the passbands of allof the analog filters to have the same transmission power, attenuationfunctions, or other characteristics. The product of the analog filtercharacteristic and the modulation scheme of a given PLC technologydetermines the effectiveness of the isolation by each analog filter. Theabsolute transmission of the filters in their respective passbands isless important than the ratio of passband to stopband, as anyattenuation differences in these filters can often be compensated forwith more injected power at the pre-filter stage and/or increasedreceiver sensitivity.

FIG. 7C shows an example of the isolation provided by the second analogfilter Filt_(B) to the Tech_(B) signal. In use, the second analog filterpasses a signal Path_(B) that is the product of the transmission power(PF_(B)) of then passband of the second analog filter and thetransmission power (P_(B)) of the Tech_(B) signal. The signals of theother technologies (Tech_(A) and Tech_(N)) are attenuated by thestopband of Filt_(B) to a power level PF_(N) that is sufficiently lessthan PF_(B) to ensure that they do not significantly interfere with thePath_(B) signal.

In some embodiments, the improved power line communication networkincludes the ability to provide increased throughput as the number ofnodes increase in the network. In particular, such increased throughputdemand typically coincides with an increased number of nodes, since moredata needs to be transmitted when multiple devices share the network.

FIG. 8A shows a simple initial installation of a single service, in thiscase IPTV (internet protocol television) delivered to the home 600 via aDSL connection 602, which is distributed (using the improved power linecommunication network) from the DSL modem 602 in the office to a TV set604 in the living room. Since the distance between the DSL modem 602 andthe TV set 604 is comparatively long, the connection C1 therebetweenpredominantly uses the low band due to its inherently greater coverage.The bandwidth provided by the low band is sufficient for the TV setbecause only a single TV channel is transmitted.

As an improved power line communication network grows (i.e. more nodesare added to it) the average distances between nodes tends to decrease.When a very complex situation is installed like that depicted in FIG. 8B(showing a complex in-home multimedia network with multiple simultaneousvideo and audio streams), connections C2-C7 are predominantlyimplemented using the high band (due to its greater throughput) over therelatively short distances present. Low band connections C8, C9, willstill be in use when their efficiency is higher than using multiple hopsof high band links. In addition, many connections (e.g. C10) will beserved by communication using both bands.

In use, a node on the network will typically discover the other nodes onthe power line through some form of synchronization that is usuallydefined within the power line technology used in one of the bands. Thenode will also identify the technology capabilities and virtual networkmembership of the detected nodes, to determine what communication willbe possible and/or allowable (for instance, whilst a detected node mayphysically have certain technology capabilities, these may be impairedby interference or restricted in use). Having identified the physicallypossible and allowable communications, the sending node will decide thebest path for sending/receiving data, based on factors such as the typeof data to be communicated, how it is ranked in the QoS (quality ofservice) and the available channel capacity.

FIG. 9 illustrates a method by which one communication node can discoverother communication nodes on a network using different widebandfrequency ranges. In a send step 910, a first communication is sent froma first communication node over a power line using a first widebandfrequency range, the first communication including data configured toidentify a second communication node configured to communicate in thefirst wideband frequency range. This first communication is configuredto solicit a response from other communication nodes, such as the secondcommunication node, that are configured to communicate over the firstwideband frequency.

In a receive step 920, a response to the first communication is receivedfrom the second communication node.

In a send step 930, a second communication is sent from the firstcommunication node over the power line using a second wideband frequencyrange, the second communication including data configured to identify athird communication node configured to communicate in the secondwideband frequency range. This second communication is configured tosolicit a response from other communication nodes, such as the thirdcommunication node, that are configured to communicate over the secondwideband frequency.

In a receive step 940, a response to the second communication isreceived from the third communication node. If the second communicationnode is further configured to communicate using the second wideband,then receive step 940 may include receiving communications from both thesecond and third communication nodes.

In a determine step 950, a communication strategy based on the responseto the first communication and the response to the second communication.This determination may include selections of widebands or standards touse. This determination may include a strategy for communication betweenthe third and second communication nodes, e.g., should the communicationbe direct or should the first communication node function as a relay. Insome embodiments, Send Steps 910 and 930 include using differentstandards in addition to or as an alternative to using differentwidebands.

In an optional communicate further step communication is executedaccording to the determined communication strategy.

FIG. 10 illustrates a method in which a first communication nodecommunicates simultaneously with both a second communication node and athird communication node. The communication is optionally independent.The first communication node optionally operates as a relay between thesecond communication node and the third communication node.

In a first communication step 1010, first data is communicated between afirst communication node and a second communication node over a powerline, using a first wideband frequency range. In a second communicationstep 1020, second data is communicated between the first communicationnode and a third communication node over the power line, using a secondwideband frequency range separate from the first wideband frequencyrange, the first data and the second data being communicatedsimultaneously.

The method illustrated in FIG. 10 is optionally employed where thesecond communication node functions as both the second and the thirdcommunication node. In these embodiments a first part of data can besent using the first wideband frequency and a second part of data can besent using the second wideband frequency. In these embodiments, the useof the two different wideband frequencies is optionally configured tomaximize total data bandwidth.

FIG. 11 illustrates a method in which a communication node receivessimultaneous signals using at least two different widebands. Dataencoded in these signals is optionally independent and may be receivedfrom different communication nodes on a network. The data may also betransmitted and/or decoded using different communication standards.

In a receive first signal step 1110, a signal is received over a powerline. This signal includes encoded data. The encoding may include any ofthe various methods known for encoding data on a time dependent signal.

In a separate component step 1120, a first component of the signal, in afirst wideband frequency range, is separated from a second component ofthe signal, in a second wideband frequency range. In variousembodiments, each of the first wideband frequency range and the secondwideband frequency range are at least 5, 7, 10, 12, 15, 20, 100, and/or200 MHz wide. For example in one embodiment, the first widebandfrequency range is at least 10 MHz wide and the second widebandfrequency range is at least 5 MHz wide. In one embodiment, the firstwideband frequency range is at least 10 MHz wide and the second widebandfrequency range is at least 200 MHz wide. In some embodiments, theseparation of signal components is performed using analog bandpassfilters. For example, one bandpass filter may be configured to isolatethe first wideband frequency range and another bandpass filter may beconfigured to isolate the second wideband frequency range.

In a process step 1130, the first signal component and the second signalcomponent, separated in separate component step 1120, are eachseparately processed. This processing is typically preformed inparallel. For example, one signal component may be processed using lowband analog path LB₁ and the other signal component may be processedusing high band path HB₁, Low band analog path LB₁ and high band pathHB₁ optionally share one or more component. Process step 1130 results intwo sets of digital data.

In a provide step 1140, the two sets of digital data are provided to oneor more applications. The two sets of digital data may be usedindependently.

FIG. 12 illustrates a method in which a communication node sendssimultaneous signals using at least two different widebands. Dataencoded in these signals in optionally independent and may be intendedfor different communication nodes on a network. The data may betransmitted and/or encoded using different communication standards.

In a receive data step 1210, digital data is received from one or moreapplications. This data is optionally independent. In an encode step1220, a first part of the digital data is encoded into a first signalwithin a first wideband frequency range, at least part of the firstwideband frequency range is optionally less than 30 MHz. This encodingmay be performed using, for example, low band analog path LB₂.

In an encode step 1230, a second part of the digital data is encodedinto a second signal within a second wideband frequency range, at leastpart of the second wideband frequency range is optionally greater than30 MHz. This encoding may be performed using, for example, high bandpath and HB₂. Encode Step 1230 and Encode Step 1220 may be performed inparallel.

In a combine step 1240, the first signal and the second signals arecombined to generate a combined signal. This step is optionallyperformed using Tx Coupling 196, or HB Tx Coupling 154 and LB TxCoupling 160. For example, using HB Tx Coupling 154 and LB Tx Coupling160 the combination may occur as both signals are coupled to a powerline.

In a send step 1250, the combined signal is sent over a power line.Different parts of the combined signal may be sent simultaneously andmay be intended for different destinations. Several embodiments arespecifically illustrated and/or described herein. However, it will beappreciated that modifications and variations are covered by the aboveteachings and within the scope of the appended claims without departingfrom the spirit and intended scope thereof. For example, the techniquesdescribed herein may be in used in household, industrial and/or vehiclepower systems. Further various elements illustrated and discussed hereinmay be embodied in software (stored on computer readable media),firmware, and/or hardware. These element forms are generally referred toherein as “logic.”

The embodiments discussed herein are illustrative of the presentinvention. As these embodiments of the present invention are describedwith reference to illustrations, various modifications or adaptations ofthe methods and or specific structures described may become apparent tothose skilled in the art. All such modifications, adaptations, orvariations that rely upon the teachings of the present invention, andthrough which these teachings have advanced the art, are considered tobe within the spirit and scope of the present invention. Hence, thesedescriptions and drawings should not be considered in a limiting sense,as it is understood that the present invention is in no way limited toonly the embodiments illustrated.

1. A communication network comprising: three communication nodes, eachincluding a first analog filter, each configured to communicatesimultaneously and independently over a power line with the other twocommunication nodes using a plurality of widebands, wherein a high bandof the plurality of widebands has a minimum frequency greater than 30MHz, wherein a low band of the plurality of widebands has a maximumfrequency of about 30 MHz, wherein the first analog filter of eachcommunication node comprises a low pass filter, and wherein each of thethree communication nodes is configured to transmit signals in the lowband with a low band transmission power spectral density and configuredto transmit signals in the high band with a high band transmission powerspectral density and wherein the low band transmission power spectraldensity is approximately one thousand times greater than the high bandtransmission power spectral density.
 2. A communication networkcomprising: three communication nodes, each including a first analogfilter, each configured to communicate simultaneously and independentlyover a power line with the other two communication nodes using aplurality of widebands wherein a high band of the plurality of widebandshas a minimum frequency greater than 30 MHz, wherein the first analogfilter of each communication node comprises a first analog high passfilter and each communication node comprises: a high band receiverincluding the first analog high pass filter, a first demodulator, and afirst ADC coupled between the first analog high pass filter and thefirst demodulator; a low band receiver including a first analog low passfilter configured to exclude frequencies above about 30 MHz, a seconddemodulator, and a second ADC coupled between the first analog low passfilter and the second demodulator; and a transmitter including a secondanalog filter, a first modulator, and a first DAC coupled between thesecond analog filter and the first modulator.
 3. The communicationnetwork of claim 2 further comprising a second modulator coupled to thefirst DAC.
 4. The communication network of claim 2 wherein the secondanalog filter of the transmitter comprises a second analog high passfilter.
 5. The communication network of claim 2 wherein the secondanalog filter of the transmitter comprises a second analog low passfilter configured to exclude frequencies above about 30 MHz.
 6. Acommunication network comprising: three communication nodes, eachincluding a first analog filter, each configured to communicatesimultaneously and independently over a power line with the other twocommunication nodes using a plurality of widebands wherein a high bandof the plurality of widebands has a minimum frequency greater than 30MHz, wherein the first analog filter comprises a first analog high passfilter and each communication node comprises: a high band transmitterincluding the first analog high pass filter, a first modulator, and afirst DAC coupled between the first analog high pass filter and thefirst modulator; a low band transmitter including a first analog lowpass filter configured to exclude frequencies above about 30 MHz, asecond modulator, and a second DAC coupled between the first analog lowpass filter and the second modulator; and a receiver including a secondanalog filter, a first demodulator, and a first ADC coupled between thesecond analog filter and the first demodulator.